Perhaps the weakest link in the US electrical system

Hey there! Correction time (and more thoughts!): THHN wire is what’s inside the sheathing of Romex, which is actually classified as NM-B cable/wire. As in, the conducting wires are THHN, the whole thing together is an NM-B cable. Yep. So there’s that. Also, I want to be clear that of the problems we have, this isn’t a huge one. Generally, when things get hot because of overloading, it’s at the connection point and not in the wire. For instance, a lot of electrical fires start at the plug/socket interface either because the connection is poor, there could be corrosion, etc. And sometimes they can happen when nothing is overloaded! This is one of the circumstances in which arc-fault circuit interrupters can save lives. It may well be the case that very few fires are started because of the problem we’re discussing in this video. Especially since outside of certain high-draw devices, the risk of overloading the actual conducting wire is low in the first place. That’s why I am comfortable using them! That said, I remain perplexed that this is an issue we’ve let persist. Most electrical fires aren’t the result of a single thing; they’re a cascade of individually not-great circumstances combining to make a bad situation. In order to reduce the risk of fires, we’ve continually been making the not-great things less bad. That way an increasingly large number of bad circumstances have to align for a fire to happen. Simply put, I think allowing unfused 16 gauge extension cords into the market is a potentially bad link in the chain that we could probably do with cutting out. In fairness, it used to be much worse. 18 gauge (maybe even 20 gauge) extension cords were available many years ago, but we at least had the sense to make 16 the minimum as time went on. However, as I hope I’ve demonstrated here, that can still be problematic. Pulling 20 amps through that cord made it get very hot quite quickly.

You DO realize that with proper protection everywhere, my channel won't be able to operate, right?!

"I plugged these two resistive heaters into this thin copper filament, and now I have three resistive heaters!"

As an HVAC journeyman 20 years deep. This is probably the best video I have seen on basic household amp ratings and why they matter. Well done

EXCELLENT video. I'd like to add: - 6 ft accessories require outlets every 12 feet, not every 6, since you get 6 to the left, and 6 to the right of the accessory - fire marshals HATE chained extension cords - overloading extension cords also softens and melts insulation in the cord, and can lead to an arc and sparking, which ignites stuff (I've had a hair dryer cord IGNITE while I was drying my hair due to the cord softening at the dryer, so like RIGHT by my hand) - fuses in 120vac plugs used to be common (I still have a few here, most are made of bakelite and use the bigger glass fuses) - using an extension cord as a splitter isn't really all that economical - a super cheap 5 outlet power strip costs about the same as a standard 3 outlet extension cord and I LOVED your 100mph analogy for "safer"

Talent: The ability to get people to happily spend 25 minutes learning about extension cords

My in-laws are deaf and, as such, we always have the CC on. I really appreciate that you manually create the CC. it is a noticeable difference when I watch your vids. I love the "Overloadedly Smooth Jazz" at the end.

As somebody who’s been an engineering hobbyist for quite some time now, I can confidently say this guy is the absolute best at dumbing things like this down enough for the average person to understand.

A helpful way to understand why gauge numbers seem to be backwards (as in a smaller # means bigger wire) is to remember that they are indicative of how many of something can be made from a given amount of material. In this case, copper for wire. For example, let’s suppose I can make 14 wires from one pound of wire. If I decide instead to use up that pound of copper and only make 12 wires of the same length, then they would necessarily be a little thicker because I had more copper for each one.

Space Heater: "Do not use with extension cord!" Also Space Heater: "Here's an incredibly useless 3 foot cord. Enjoy!"

For my final in my high school speech class I demonstrated making pancakes right in the classroom. To do this I brought in a (rather modest) countertop griddle and, to reach the wall outlet... a flimsy brown extension cord. I didn't think twice about it. ...until partway through the demonstration-speech there was a flash of light as the cord literally melted away from the plug in the wall. We had to get a maintenance guy to come safely remove the now-bare-wire plug from the wall outlet. (He also brought a (better) extension cord, I finished my speech, and got a 99%. And the class got sample pancakes. :)

10:12 Who also had this drawing in mind there, with the dog sitting at a table, thinking "It's fine", while the whole room is on fire?

Spot on. As an electrician I see this all the time. Another thing I run into is people using outdoor rated cords indoors. They think because the extension cord is thicker that it can handle more load. However, it’s still just a 16AWG cord it just has heavier insulation on it to prevent it from cracking in the cold. But used inside it’s like running an extension cord under the carpet, the heavier insulation causes it to heat up more. Heat is what damages the insulation. It caused stress fractures, which causes arcing, which causes heating, which causes fires! So, over heating your cable is what is bad and like you said, that’s why they have over load protection on building wiring. You size the wire to the load and the breaker to the wire. AFCI breakers are used in new houses now to protect the extension cords that are plugged into the walls.

I work at a hardware store. One lady came in complaining her fuses kept blowing. So I sold her more, she came back a week later for more. She had told me she was only using a hot plate. Her friend ran into her. Turns out it was a small range type thing, microwave, coffeemaker and more. It was like everything in her kitchen was running off the same outlet. She wanted higher fuses. I said no it's a fire hazard. "But what if I'm home" no lady it's in your walls. You cannot see it.

Seriously, I love the line "the only conclusion I feel comfortable making here, is that I don't have enough information to come to a meaningful conclusion." We live in a world, and in particularly on an internet, that is so often devoid of nuance. Combined with a toxic mentality that generally prohibits admitting that you don't know something, and basic levels of communication and debate break down. You're one of the last few bastions of rational discourse and I applaud that. Thank you, Alec.

Ring circuits are a brilliant idea, it means that no matter if the socket is the first or the last on the circuit from one side, the same amount of current can be safely drawn. Since each plug is fused and can only draw a max of 13A, it’s impossible to overload a circuit without blowing the fuse in the plug or tripping the breaker. Also it’s been standard for GFCI breakers here for a while now.

100 years and I have a whole bunch of extension cords that are cheap that I bought and plug-in air conditioner into them all summer-long melted them and I didn't understand why until now you probably just saved my life and my family's life thank you for making this episode and explaining it in the way that everybody can make sense of it thank you

Throwing your leg up on the table with more extension cords was a pretty solid bit.

You never met my friend's neighbor. He took the fuses out of Christmas lights and replaced them with a nails or a bit of wire. The reason he did this was "the stupid fuses keep blowing when I plug all the strands in on this run". Yes this man systematically defeated every single fuse in his Christmas lights because he was plugging too many in to each other and was irritated that they kept blowing fuses.

Hi from the UK, where ring mains are the norm and spares (daisychaining) are frowned upon. All my plugs have fuses in them, and my 50M (100ft) real has an overcurrent fuse on the plug AND a thermal cut out on the reel. Let me give you an example. Last summer, I was having my kitchen remodelled, so I had to set up a temporary kitchen in the dining room. I had a kettle, electric hob, halogen oven, toaster,, George foreman grill, microwave, and 2 lamps the closest plug socket I had available was 20 M away at next to the front door and the remainder of the reel was wrapped up. You can imagine my mum's surprise as when she was making a cup of tea, beans, sausage, bacon waffles so kettle, foreman, microwave, and toaster on the reel got really hot and tripped out. She went checking the fuses at the breaker box, all on, changed the fuse on the plug nothing, turns out that the breaker, and plug fusenhad not tripped instead the thermal cut out had tripped. I unravelled the reel and left the 30 M cable loose behind a cupboard reset the thermal cur our and then it was fine for 3 months. If that had been America it would have blown up on night one.